Refrigeration system with liquid and vapor pumps



March 17, 1970 A. F. LOFGREEN ETAI- 3,500,656

REFRIGERATION SYSTEM WITH LIQUID AND VAPOR PUMPS Filed April 18, 1968Har/syl?. Ooygbarn Hw drewfla/reen Ey Affe/*neg United States Patent OU.S. Cl. 62--196 5 Claims ABSTRACT F THE DISCLOSURE A refrigerationsystem including, an elongate evaporator with inlet and outlet ends, anelongate low pressure condenser with inlet and outlet ends and meansconnecting the inlet end of said condenser with the outlet endY of theevaporator, a liquid vapor phase separator connected with the outlet endof the low pressure condenser, a positive displacement heat pumpconnected with and draining liquid from the separator, an elongate highpressure condenser with inlet and outlet ends, a delivery line from theheat pump to the inlet end of the high pressure condenser, an electromagnetically controlled metering valve in the delivery line, a venturiin the delivery line downstream of the metering valve to accelerate therate of ow of refrigerant therethrough, a temperature sensing bulb inthe line downstream of the venturi connected with the metering valve, avapor pump connected with and extracting vapor from the separator andconnected with the delivery line downstream of the venturi and injectingvapor into said line, a receiver connected with the outlet end of thehigh pressure condenser and llow control and expansion means between thereceiver and the inlet end of the evaporator to control the rate of owof high pressure liquid refrigerant from the receiver and into theevaporator.

This invention relates to a novel, improved refrigerating system and ismore particularly concerned with a system wherein the refrigerant ispumped when in a liquid state, to effect the necessary ilow ofrefrigerant and to that extent is distinguishable from conventionalsystems employing absorption or compression principles.

In general, thermally operated or absorption type refrigeration systemshave been less than moderately successful because of an inherentlyrelatively low coefficient of performance. A major shortcoming ofabsorption type systems resides in the large quantities of rejected heatand the requirements of bulky accessory equipment, such as condensers,cooling towers and the like.

Further, absorption type refrigeration systems are normally such thatthey must be carefully and accurately installed and set, to the end thatthey are, in addition to being ineicient, unsuitable for use inautomobiles or other like installations where minimal space is availableand/or where the systems are subject to being moved about and theirposition varied.

In general, compression type refrigeration systems are more versatilethan absorption type systems and are such:

that they can be made small and compact and are unaffected by movementor change in position. Accordingly, this type of system is suitable forand finds wide use in automotive air conditioning systems or units. Theprincipal shortcoming in compression type systems resides in the factthat large, heavy and inefcient compressors capable of handling largevolumes of gaseous refrigerants, must be provided.

To illustrate the efficiency of the ordinary compression typerefrigeration system, the ordinary automotive air conditioning unitincludes a compressor driven by the automobile engine, which compressordraws from ten to ice fifteen horsepower of work energy from the engineto effect operation of the system.

It is well known and recognized that liquids can be etliciently moved bypumps, while moving gases by means of pumps or compressors, is, bycomparison, very inefficient.

A refrigerant, such as Freon #12, when in a liquid state, is aout 1/77the volume of a like mass of that refrigerant when in a gaseous state;accordingly, it will be apparent that a given mass of liquid Freon, #l2can be pumped and moved much more efficiently and with the expenditureof a small fraction of the power that would be required to move a likemass of gaseous Freon #12.

In an ordinary compression type refrigeration system, the work energyemployed to effect its operation is introduced into the refrigerant whenit is in a gaseous state by means of a mechanical compressor, with theresult that the refrigerant is being worked upon when it is in that,state where it is least capable of absorbing the desired work energy.

An object of our invention is to provide a refrigeration system whereinthe refrigerant is worked upon and work energy is imparted into, when ina liquid state and by means of a pump.

It is an object of our invention to provide a refrigeration system whichincludes a fractional horsepower liquid moving and heat generating pumpand a fractional horsepower vapor pump, the aggregate power of the pumpsbeing less than one horsepower and the output of the system being equalto the output of compression type systems requiring from ten to fifteenhorsepower to operate.

It is another object of our invention to provide a liquid vapor phaseseparator type accumulator at the discharge end of an evaporator, apositive displacement liquid moving and heat generating pump to drawliquid refrigerant from said accumulator and a vapor pump to drawgaseous refrigerant and refrigerant vapor from said accumulator wherebythe volume of refrigerant contained in said accumulator is maintainedsuiciently low to receivel the ilow of refrigerant from the evaporatorat all times.

It is yet another object of our invention to provide a system of thecharacter referred to wherein the liquid moving and heat generating pumpmoves and discharges liquid refrigerant from the low pressure to thehigh pressure side of the system. Accordingly, it is an object of thisinvention to provide a system wherein the movement of liquid refrigerantis employed to move and circulate gaseous refrigerant through thesystem.

Another object of the present invention is to provide a system of thecharacter referred to wherein gaseous or vaporous refrigerant dischargedby the vapor pump is combined with the refrigerant issuing from theliquid pump, whereby the gaseous and vaporous refrigerant, being at ahigher temperature and resulting higher pressure, induces vaporizationand expansion of the liquid refrigerant and resulting increased velocityor rate of ow of the pumped'refrigerant flowing through the highpressure side of the system.

Yet another object of our invention is to provide a system of thecharacter referred to including a venturi at the discharge side of theliquid pump, upstream of the connection with the discharge of the vaporpump, which venturi maintains sufficient head pressure at the dischargeside of the liquid pump to maintain the refrigerant in a liquid stateand which creates a pressure drop at its downstream side whereby theliquid refrigerant expands sufficiently to accelerate its rate of ow andcools sufficiently to create a temperature and resulting pressure dropso that the necessary pressure differential between the discharge of thevacuum pump tnd the line pressure is sufficient to assure injection ofhe discharge of the vacuum pump into the line.

It is a further object and feature of our invention to Jrovide ametering means between the liquid pump and he venturi to regulate thevrate of flow of refrigerant nto and through the venturi and to providemeans, re- :ponsive to the temperature of the refrigerant down- ;treamof the Venturi and operating the metering means.

Still further, it is an object and feature of the present nvention toprovide a liquid pump which is a positive lisplacernent, heat generatingpump and serves to heat :he liquid refrigerant whereby it is readilyvaporized 1nd transformed to a gaseous state when flowing through heventuri and mixing with the discharge of the vapor pump and whereby thegaseous refrigerant entering the nigh pressure condenser is at a hightemperature.

It is to be noted that the pumps and the several means lirectly relatedto them, at the -high pressure side of the system, do not perform thefull corresponding function 3f compressors intrue compression typesystems, but serve, primarily, to establish and maintain a highpressure, high velocity flow of refrigerant at the downstream end of thehigh pressure side of the system, which high pressure, high velocity owcreates the necessary and desired operating pressure and temperaturedifferential below the high and low pressure sides of the system.

The foregoing and other objects and features of our invention will belfully understood from the following detailed description of a typicalpreferred form and application of our invention, throughout whichdescription reference is made to the accompanying diagrammatic drawingof our system.

The system that we provide includes a plurality of interconnected andrelated refrigerant handling and conducting components, parts and means,and defines a circuit having high and low pressure sides.

The high pressure side of the circuit includes, generally, refrigeranttransporting means T, a condenser C, a receiver R, and flow controlmeans F.

The lower pressure side of the circuit includes an evaporator E and anaccumulator A.

The evaporator E is shown as a direct expansion type evaporator coilhaving an inlet end connected with the flow control means F of the highpressure side of the system and into which liquid refrigerant isintroduced. The refrigerant introduced into the evaporator E flowstherethrough, expands partially or totally into vapor and/or gas,absorbing heat Afrom the ambient atmosphere. The evaporator E has anoutlet or discharge end 11 which is connected with the low pressurecondenser K, or directly with the accumulator A.

The accumulator A is a liquid vapor phase type accumulator and consistsof a closed tank or vessel 14 with an inlet opening or fitting 15 withwhich the outlet 11 of the evaporator is connected, a liquid outletopening or fitting 16 at its lowermost or bottom side and a vaporgasopening or fitting 17 at its uppermost or top side.

The accumulator A is adapted to receive the refrigerant discharged fromthe evaporator.

The refrigerant transporting means T of the high pressure side of thesystem is intended to perform the function of a compressor in acompression type refrigeration system or a generator (boiler) in a heatabsorption reprovided with a restricted outlet or a flow bean at itsoutlet to create a back pressure which increases the internal pressuresin the pump and so that a predetermined portion of the work energyimparted into the pump is transformed into heat energy and heat therefrigerant being workedfupon Aby the pump. l

The gas or vapor pump V can be of any type or design of pump suitablefor moving gases and vapors, suchY as a vane type or diaphram type ofpump. The pump V can be driven by any suitable prime mover, and, inpractice, is driven by an electric motor E.

The inlet side of the pump L is connected with the liquid outlet fitting16 of the accumulator A by a suction line 18 and the inlet side of thepump V is connected with the gas outlet fitting 17 of the accumulator ofa suction line 19.

The suction line 18 is shown provided with a check valve 18 to prevent areverse flow or surge of refrigerant in the line 18 and from the pump Linto the accumulator A.

Connected with the discharge side of the liquid pump L and extending toand connected with the condenser C is a delivery line 20.

The fiow accelerating means M is engaged in the line 20 and is adaptedto accelerate the rate of flow of refrigerant Vin the line and issuingfrom the pump L.

'Ihe means M is shown as a simple venturi 21 arranged in the line 20.

metering valve frigeration system and to that extent may be consideredas a transporting means. The means T may also and properly be defined asa ow augmenting means, the function to which is to accelerate the ow ofrefrigerant in the high pressure side of the system to effect anoperative pressure differential between the high and low pressure sidesof the system.

The means T includes a liquid moving and heat generating pump L, a vaporpump V, flow accelerating means M related to the pump L and vaporinjection means I.

The pump L is preferably a two-stage type positive displacement pump,such as a positive displacement pump The function of the means M orventuri is to accelerate the rate of iiow of liquid refrigerant in theline 20 and at the same time create a presure drop at or adjacent thedischarge end of the venturi which causes a portion of the acceleratedliquid to vaporize whereby the accelerated ratey of flow does notdiminish or diminish rapidly or noticeably downstream of the venturi. 'l

It is to be noted that the means M or venturi 21 creates a back pressureor head in the line 20 between the pump L andthe venturi, which headinhibits premature vaporization of the refrigerant in the line betweenthe pump and the venturi.

Further, the noted limited expansion of the accelerated refrigerantdownstream of the venturi effectively cools the refrigerant and lowersits corresponding pressure.

The vapor injecting means I` can include a lateral taptting, such as'aT-fitting, in the line 20 downstream of the means M and conected with avapor line 22 extending from and connected with the discharge side ofthe vapor pump V, or can, as ilustrated, be an adjustable 23 with astraight through primary passage aligned and communicating with the line20, a lateral passage connected with the line 22, a lateral portcommunicating with the two passages, and a valve member shiftablyarranged in the port.

The temperature and resulting or corresponding pressure of the vapordelivered by the pump V and flowing through the vapor line 22 is greaterthan the temperature and pressure of the refrigerant in the line 20downstream of the venturizl. Accordingly, the vapor is injected into theaccelerated and rapidly moving flow of refrigerant in the line 20. Theinjected Vapor adds to or increases the volume of refrigerant owingthrough the line 20 and increases vthe temperature, pressure andvelocity of the refrigerant, inducing further vaporization of liquidrefrigerant. This results in further acceleration of the refrigerant inthe line 20.

The foregoing explanation of the function and `effect of the means M andI has been determined by observation of the system when in operation andwhile believed to be substantially correct, may be inaccurate in certainrespects.

If desired, a check valve 30 can be engaged in the line 20 upstream ofthe means I to prevent the possibility of high pressure vapors in theline diowing back into the venturi.

In the case illustrated, the system is shown provided with a scavengingmeans G, which means includes a secondary gas-vapor outlet 31 in theaccumulator A, and a vacuum line 32 extending between and connected withthe outlet 31 and the low pressure side of the venturi 21 of the means23.

The means G supplements the operation or function of the vapor pump Vand injecting means I and can greatly reduce the work load of the pump Vor reduce the size rand power requirements for the pump V.

In practice, a valve 33 can be arranged in the line 32 to put the meansG into and out of operation as circumstances require or as desired.

The condenser C is a conventional coil type heat exchanger and has inletand outlet fittings or openings 35 and 36 at the opposite ends of thecoil. The line 20 connects with the inlet fitting 35.

The receiver R is la simple tank or vessel to receive and collect liquidrefrigerant owing from the condenser and has an inlet opening 37suitably connected with the outlet end 36 of the condenser and an outletopening 38.

The rare, heated refrigerant, at high pressure flowing through the lineinto the condenser, is rapidly cooled and is condensed therein and isdischarged therefrom and conducted into the receiver R in a liquid stateat a low temperature and at high pressure.

The ow control means F is that means provided to conduct the cool, highpressure liquid refrigerant collected by the receiver R to theevaporator E. The means F can vary widely in form without departing fromthe spirit of this invention.

In the case illustrated, the means F includes an expansion valve 40connected with the inlet end 10 of the evaporator E and a liquid line 41extending from the expansion valve 40 to the outlet 38 of the receiverR. The opening 38 in the receiver R is at the bottom thereof and belowthe liquid level therein.

In addition to the foregoing, the means F is shown as including a flowcontrol or ow metering device, such as Ia iiow bean or, as illustrated,a metering valve 42 in the line 41 to limit and/or control the volume ofrefrigerant flowing from the receiver R through the line 41 and into,through and thence from the expansion valve 40 and into the evaporatorE.

In practice, the expansion valve 40, line 41 and valve 42 could bereplaced with a capillary tube without departing from the spirit of thisinvention, since such a substitution would constitute the use of awell-known mechanical equivalent.

The refrigerant issuing from the expansion valve 40 flows into andthrough the low pressure side of our system to complete therefrigeration cycle.

In practice, and in a system as provided by this invention, for use inan automobile air conditioning unit and using Freon #12 as therefrigerant, the electric motors operating the pumps L and V areone-half and one-quarter horsepower motors. The operating pressure atthe lower pressure side of the system is p.s.i. and the high pressureside is 125 p.s.i., creating an operating pressure differential of 100p.s.i.

In addition to the foregoing, we provide means H to control the volumeof refrigerant fiowing into and through the venturi 21. The means Hincludes an electro-magnetically actuated metering or demand valve 50 inthe line 20 between the pump L and venturi 21, a temperature bulb 51 inthe line 20 between the venturi 21 and valve 23 of the means I, and anamplifier 51 operatively connecting the bulb 51 and the valve 50.

In the event the temperature in the high pressure side of the systemincreases or drops excessively, the metering or demand valve 50 opens orcloses upon demand of the system, downstream of the venturi 21, and assensed by the bulb 51.

It will be apparent that with the means H set forth above, the operatingtemperature of the system can be advantageously set and maintaineduniform.

In addition to metering and controlling the rate of ow of refrigerantinto and through the venturi, the valve 50 also creates a flowrestriction and back pressure on the pump L and causes the pump to churnand heat the refrigerant and enhance the heating action of the pump.Accordingly, in practice, the valve 50 can serve in place of a flow beanor restricted outlet in the pump L to make it a heat generating pump andin which case the pump L is a simple, unaltered positive displacementpump.

It has been found that the heat generating capacity of the pump L isessential in starting or putting the system into operation and becomesless critical once the system is in operation, though slight heating ofthe refrigerant at all times appears to be necessary or desirable.

In operation, the pump L increases the temperature of the refrigerant-about sixty-five degrees.

In accordance with common practice, the system can be provided with adrier 60 and sight glass 61. In the case illustrated, the drier andsight glass are arranged in the liner 41.

In practice, the system can be provided with any suitable control means.In the case illustrated, the system is under control of a master switch70, which switch controls the flow of current to the motors E and E', tothe amplifier S2 and to the motor of a blower X related to theevaporator.

Since the details of the control means can vary widely without departingfrom or affecting the spirit of this invention, we will not burden thisdisclosure with further details of the control means shown or of otheralternative and more complicated control means that have provensatisfactory.

Having described only a typical preferred form and application of ourinvention, we do not wish to be limited or restricted to the specificdetails herein set forth, but wish to reserve to ourselves anymodifications and/or variations that may appear to those skilled in theart.

Having described our invention, we claim:

1. A refrigeration system including an evaporator, a liquid vapor phaseseparator receiving refrigerant from the evaporator, refrigeranttransporting means to remove refrigerant from the liquid vapor phaseseparator and to discharge it at increased pressure, a condenser tocondense the refrigerant discharged by the transporting means, areceiver collecting condensed refrigerant from the condenser and flowcontrol and expansion means between the receiver and the evaporator tocontrol the rate of flow of liquid refrigerant from the receiver andinto the evaporator, said liquid vapor phase separator including a tankhaving an inlet connected with the evaporator, a liquid outlet openingand a vapor outlet opening, said refrigerant transporting meansincluding a heat generating liquid pump connected with the liquid outletopening, and a delivery line extending from the liquid pump to thecondenser, a vapor pump connected with the vapor outlet opening, a vaporline extending from the vapor pump and vapor injecting means in thedelivery line and connected with the vapor line and introducing vaporfrom the vapor pump into the delivery line.

2. A system as set forth in claim 1 and further including means in thedelivery line between the liquid moving and heat generating pump and theinjecting means to increase the rate of ow of liquid refrigerantdelivered by the liquid moving pump and create a pressure drop in thedelivery line downstream from said liquid pump.

3. A system as set forth in claim 1, said system further including meansin the delivery line between the liquid pump and the vapor injectingmeans to increase the rate of How of liquid refrigerant delivered by theliquid pump and create a pressure drop in the delivery line downstreamfrom said liquid pump, said means including a venturi in the iiow line.

4. A system as set forth in claim 1 further including means in thedelivery line between the liquid pump and the Vapor injecting means toincrease the rate of flow of liquid refrigerant delivered by the liquidpump and reate a pressure drop in the delivery line downstream rom saidliquid pump, said means including a venturi in he flow line, and ametering valve in said ow line lpstream of the venturi and controlling`the volume of efrgerant owing through the venturi.

S. A system as set forth in claim 1 further including neans in thedelivery line between the liquid pump and he vapor injecting means toincrease the rate of ow of iquid refrigerant delivered by the liquidpump and create i pressure drop inthe delivery line downstream from aidliquid pump, said means including a venturi in the low line, and ametering valve in said ow line upstream )f the venturi and controllingthe volume of refrigerant lowing through the venturi, said meteringvalve having electro-magnetic operating means and Atemperature sensitivecontrolmeans connected withv said operating means and responsive to thetemperature of refrigerant in the delivery line downstream of theventuri.

g RefereucesCited UNITED STATES PATENTS 3,111,819 11/1963 williams62-'503 XR 1o MEYER PERLIN, Primary Examiner l Us. C1, X.R.

